A water-soluble nonionic cellulose ether has a thickening effect so that it has conventionally been used as a thickener for chemicals, a thickener for building materials, a water retention agent, a binder to be used in extrusion, a pharmaceutical additive, and the like.
As a typical method for producing a water-soluble nonionic cellulose ether, there is, for example, a method comprising the steps of adding a solution of an alkali metal hydroxide such as sodium hydroxide to pulp, adding an etherifying agent such as methyl chloride, ethylene oxide or propylene oxide for the reaction, purifying the reaction mixture, and drying the wet water-soluble nonionic cellulose ether obtained by purification, followed by grinding, or subjecting it to simultaneous drying and grinding (JP 10-158302A, JP 2006-152276A and JP 51-83655A).
In the above-mentioned method, each of hypromellose, methyl cellulose and hydroxypropyl cellulose, which is a water-soluble nonionic cellulose ether, allows an aqueous 2% by weight solution thereof to have a pH value of from 5.0 to 8.0 (the Japanese Pharmacopoeia 16th Edition).